Clakk robinson



C. ROBINSON.

Scaff'dd.

Patented Dec. 3, 1867.

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IMPBEMENT 1N scArroLo.

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TO ALL WHOM IT MAY CQNCERN:

Be it known that I, CLARK ROBINSON, of Rochester, in the county of Olmstead, and State of Minnesota, have invented a new and improved Scaifold; and I do hereby declare that the following is a full, clear, and exact description thereof, which will enable thoseskilled in the art to make and use the same, reference.being had to the accompanying drawings, forming part of this specification, in which- Figure 1 is a longitudinal vertical `section of my improved scaold, taken on the line xix, g. 2;

Figure' 2 is a. vertical cross-section of the same, taken on the line Vy y, ifig. 1.

Similar letters of reference indicate corresponding parts.

This invention relates to a portable scaffold, which isto be used by painters,'carpenters, and masons, and which can be raised or lowered at will to any desired height by the parties standing upon the platform of the scaffold.

The invention consists in the use of two uprights, which are secured to a horizontal frame, `and the inner ',sides of which are provided with ratchetsLinto which spring-bolts secured to the platformhiit. The said bolts can be easily opera-ted or thrown out of gear by those on the platform, for the purposeof lowering, while the' hoisting is done by means of ropes passing over pulleys `on the top ot` the uprights, and wound upon a windlass, which is arranged on top ofthe platform. i

A A are two uprights, made of wood or other suitable material, and of the necessary height. They are at their lower ends firmly secured in 4a wooden frame, B, which is anchored in the ground, or otherwise fastened to the same when the scaffold is to be used. At their upper ends the uprights are connected by a cross-bar, C. To the,inner sides of the uprights are secured ratchet-bars, or the uprights are provided with notches, a a, as show' in g. 1. D is the platform, which is arranged around the uprights, so as to slide up and down on the'm. A windlass, E, is secured to the'platform,and operated by a crank and gear-wheels in .the usual manner. The inner ends of two ropes, b, are secured to the windlass, pass up over pulleys c c on top of the u-prightsA, and then down again, their outer ends being secured to the platform again, so that by winding their inner ends around the windlass the platform will be raised. '.lwo spring-bolts F F are arranged on the under side of the platform, and are forced by spiral or other springs into the notches a a, so as to prevent the platform from vfalling. These bolts connect by links with cranks f and g of a rock-shaft, d, arranged across the platform to the under side of the same. To the rock-shaftY is secured .an arm or lever, e, which passesup to the upper side of the platform. By moving the same in the direction of the arrow, shown -in tig. 1, the bolts will be with drawn from the ratchet, and the platform can be made to descend by slowly unwinding the rope b from the windlass.

Claim.

I claim as new, and desire to secure by Letters Patentp -1. The uprights A, when provided with notches-a a, in combination with' the spring-bolts F, and'leiverie, for the purpose of supporting the platform, and for lowering the same when required.

2. The wndlass E, in combination with the 4frame A, platform D, and spring-bolts F, all made and operating substantially as` and for the purpose herein shown and described.

4 CLARK ROBINSON. p

Witnesses:

JAMES B. OTT, 'W. W. MAYO. 

